Human erythrocytes express GLUT5 and transport fructose
II Concha, FV Velasquez, JM Martinez, C Angulo, A Droppelmann, AM Reyes, JC Slebe, JC Vera and DW Golde
Instituto de Bioquimica, Facultad de Ciencias, Universidad Austral de
Chile, Valdivia.
Although erythrocytes readily metabolize fructose, it has not been known
how this sugar gains entry to the red blood cell. We present evidence
indicating that human erythrocytes express the fructose transporter GLUT5,
which is the major means for transporting fructose into the cell.
Immunoblotting and immunolocalization experiments identified the presence
of GLUT1 and GLUT5 as the main facilitative hexose transporters expressed
in human erythrocytes, with GLUT2 present in lower amounts. Functional
studies allowed the identification of two transporters with different
kinetic properties involved in the transport of fructose in human
erythrocytes. The predominant transporter (GLUT5) showed an apparent Km for
fructose of approximately 10 mmol/L. Transport of low concentrations of
fructose was not affected by 2-deoxy-D-glucose, a glucose analog that is
transported by GLUT1 and GLUT2. Similarly, cytochalasin B, a potent
inhibitor of the functional activity of GLUT1 and GLUT2, did not affect the
transport of fructose in human erythrocytes. The functional properties of
the fructose transporter present in human erythrocytes are consistent with
a central role for GLUT5 as the physiological transporter of fructose in
these cells.
Volume 89,
Issue 11,
pp. 4190-4195,
06/01/1997
Copyright © 1997 by The American Society of Hematology
